This invention relates to exhaust processors for filtering particulate matter from a combustion product, and particularly to an exhaust processor having a by-passable filter regeneration system. More particularly, the present invention relates to an exhaust processor assembly with a processor housing providing a main passageway through the housing having a substrate mounted therein for solid particle filtration and an auxiliary passageway through the housing bypassing the substrate and containing a muffler for attenuating noise of combustion product diverted through the auxiliary passageway during regeneration.
It is well known in the art to employ a diesel particulate trap which filters combustion product from an engine by passing the combustion product through a filter element or substrate to remove solid particles and pollutants before the combustion product is released to the atmosphere. These substrates must periodically be cleaned to restore functionality to the trap. Heat is applied to each substrate to burn and oxidize trapped carbon particles removed from the combustion product in the substrate. During this cleansing or "regeneration" it is advantageous to divert the combustion product through an auxiliary passageway bypassing the substrate to allow regeneration of the substrate by a burner or heat source.
One object of the present invention is to incorporate a muffler into an exhaust processor assembly to meet acceptable noise standards by attenuating exhaust noise and also to provide an obstacle to easy disablement of an exhaust filter in the assembly by tampering with the exhaust filter while leaving the muffler in a functioning state.
Another object of the present invention is to provide muffler means, situated in a flow passage bypassing an exhaust filter, for attenuating noise produced by the exhaust as it is diverted through the bypass flow passage during regeneration of the filter.
Yet another object of the present invention is to provide a single housing including means for treating a combustion product and means for attenuating noise from the combustion product during regeneration of the treating means.
Still another object of the invention is to house an exhaust filter, substrate, or other combustion product treatment means in one flow passage of an exhaust process or assembly and an acoustic muffling device or other noise attenuation means in a second flow passage of the exhaust process or assembly.
A further object of the invention is to divide an upstream portion of an exhaust processor housing into a first flow passage containing a substrate and a second flow passage bypassing the substrate and place a muffler in a downstream portion of the housing to receive combustion product from both of the first and second flow passages before the combustion product is discharged from the housing so that noise of combustion product conducted through either a main or substrate bypass passage is attenuated by a muffler in the housing.
According to the present invention, an exhaust processor assembly includes a housing having an inlet for introducing combustion product from the housing and an outlet for discharging the combustion product from the housing. A partition is positioned within the housing to define first and second passageway means or flow passages extending through the housing to provide communication between the inlet and the outlet. A substrate is situated in the first flow passage. The substrate collects particulate matter entrained in the combustion product as the combustion product passes through the first flow passage. A muffler is situated in the second flow passage to attenuate noise generated by combustion product passing through the second flow passage.
In preferred embodiments, a top shell and a complementary bottom shell are joined together to form the housing. The partition includes an outer flange trapped between portions of the top and bottom shells to secure the partition in its position within the housing. The partition and top shell cooperate to define a portion of the second flow passage, and the partition and the bottom shell cooperate to define a portion of the first flow passage.
The muffler extends between the partition and the top shell to provide means for reversing the direction of combustion product flow to attenuate noise generated by the combustion product. The reversing means includes a plurality of baffles interconnecting the top shell and the partition to define a plurality of chambers. At least two tubes are configured to interconnect selected chambers to define means for conducting combustion product through the muffler toward the outlet.
According to other preferred embodiments of the present invention, the top and bottom shells cooperate to define a third flow passage interconnecting the first and second flow passages and the housing outlet. The muffler is situated in the third flow passage. The muffler includes a plurality of baffles interconnecting the top and bottom shells to define a plurality of muffler chambers in the third flow passage. The muffler further includes a plurality of first tubes arranged to extend through the baffles to define means interconnecting selected muffler chambers for communicating combustion product from the second flow passage to the housing outlet.
In one of such other embodiments, the muffler includes a second tube arranged to extend through the baffles to interconnect the first flow passage and the housing outlet without introducing combustion product passing through the first flow passage into any of the muffler chambers. In another of such other embodiments, the second tube is perforated or otherwise formed to include means for communicating combustion product passing therethrough to at least one of the muffler chambers.
One feature of the present invention is that a muffler is situated in the passageway bypassing the substrate. Advantageously, this muffler acts to attenuate noise generated by combustion product passing therethrough during regeneration of the substrate.
Another feature of each of the embodiments is the provision of a muffler and a substrate for treating combustion product from an engine in a single housing. The likelihood that someone will attempt to disable or circumvent the substrate is substantially reduced because of inclusion of the substrate and the muffler in a single housing. Location of the substrate inside the muffler housing makes it difficult for a mechanic or vehicle owner to disable the substrate without damaging the housing and muffler. Any damage to the muffler could cause the vehicle not to comply with mandatory vehicle noise emission standards. Thus, it is unlikely that someone would choose to sacrifice the muffler and housing to circumvent the substrate. Advantageously, such a system will help to ensure that untreated combustion product will not be discharged into the environment because of intentional tampering with vehicle pollution control systems.
Yet another feature of the invention is the provision of a muffler subassembly that extends from an inner wall of the top shell to an inner wall of the bottom shell of the housing. Advantageously, such a feature utilizes the maximum spatial volume available within the housing for the muffler, thereby increasing sound attenuation of the combustion product bypassing the substrate during regeneration.
Still another feature of the invention is the provision of apertures in the vent tubes extending through the muffler subassembly from the substrate to the outlet means. Combustion product passing through the vent tubes can enter at least one of the chambers in the muffler. Advantageously, such a configuration increases attenuation of combustion product passing from the substrate to the outlet. Reversing flow of combustion product through the apertures permits the utilization of the volume in the muffler subassembly to further attenuate combustion product exiting the substrate.
In this specification and in the claims, the words "an exhaust processor" are intended to refer to various types of catalytic convertors and processors, diesel particulate filters, and other particulate traps in connection with which the invention may be used.
Additional objects, features, and advantages of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of preferred embodiments exemplifying the best mode of carrying out the invention as presently perceived.